For the evaluation of the effect of intraarterial chemotherapy with CDDP(cis-diaminedichloroplatinum) in the treatment of osteogenic sarcoma, we compared radiographic findings of magnetic resonance imaging(MRI) and intraarterial digital subtraction angiography(IA DSA) with the degree of tumor necrosis in pathologic speciments. The decrease in neovascularity and tumor stain in IA DSA showed good correlation with tumor response(necrosis) to IA chemotherapy. MRI was useful in the localization of intra-and extramedullary tumor. and detection of skip metastases, but signal intensity changes showed poor correlation with tumor response to chemotherapy. In gadolinium diethyltriamine pentaacetic acid enhanced MRI(Gd-DTPA MRI), the enhancing areas closely correlated with the areas of tumor stain IA DSA. In conclusion, IA DSA is a good imaging tool and Gd-DTPA MRI is expected to become a more useful modality in the evaluation of tumor response to chemotherapy in osteogenic sarcoma.